What is Nuclear Energy?

In past posts I’ve talked about the arguments against nuclear energy, and refutations to those arguments (1. Basics2. Capacity3. Waste4. Cost). But what is nuclear energy? In this post, we will explore how nuclear power is generated.

So, what exactly is nuclear energy?
Nuclear energy is the process of generating electricity by means of nuclear fission. As D.J. from The Pragmatic Environmentalist so eloquently put it, “Hot rocks heat water, water boils, steam spins turbine.”

Fission is the breaking apart of an unstable atom (uranium, for this lesson). When the atom breaks apart, it releases a great deal of energy. Left to their own devices, a fissile atom will split apart spontaneously. When this happens, a uranium atom will release energy as well as a couple neutrons. These neutrons move too quickly to strike and break apart nearby atoms, so a clump of uranium will just slowly dissipate energy and eventually become lead.

While each fission event is itself spontaneous, the time in which half of all the atoms have fissioned is measurable, and this is called the half-life. The longer half-life something has, the less “active” (or radioactive) it is considered to be, as a given quantity of uranium can only fission so many times. This is why something with an extremely long half-life is generally less hazardous than something with a shorter half-life; it may give off the same amount of energy in the end, but over a longer period of time.

“So how do we harness this energy?”
First, uranium is separated into U238 and U235. U235 is considered fissile uranium (it is more fissile than U238), so we need to enrich our clump of uranium to about 4% U235. Uranium is naturally about 0.7% U235 and 99% U238. These percentages matter not only for ideal fuel conditions, but also because weapons-grade uranium is defined as U235 enriched to 90% or more; uranium used for nuclear power plants cannot be used for weapons without a lot of additional processing (it can’t just be stolen or taken by terrorists and used as-is).

Once our uranium is about 4% U235, we can put it into a reactor. A traditional reactor houses the fuel (uranium), water, and control rods. When fissile uranium decays (splits apart), those neutrons that are released are slowed by the water in the reactor, and this allows them to strike nearby fissile atoms and break them apart, thereby releasing more neutrons and creating a chain reaction.

Control rods contain neutron absorbents such as boron, which acts to slow or even stop the chain reaction by reducing the amount of available neutrons needed to sustain the chain reaction.

“Ok, but how do you get energy out of all this?”
Well, this is the process of “hot rocks heating water.” This whole process creates a lot of heat, and in the water, this produces steam. Everything beyond that is essentially steam generated power; the steam turns turbines, which produces electricity. That electricity is then put onto the grid or wherever it is needed.

One of the coolest things about this whole process is that there is no CO2 emission; this method of nuclear power generation only produces steam, or H2O, so it is a carbon-free source of electricity. Nuclear plants are powerhouses that can compete with coal and gas with the amount of power that they generate, and nuclear power is always there when we need it.

To quote Mike Conley, author of Roadmap To Nowhere, “Go nuclear, or go Extinct.”